Rain

Rainwater harvesting provides an independent water supply during regional water restrictions and in developed countries is often used to supplement the main supply. It provides water when there is a drought, can help mitigate flooding of low-lying areas, and reduces demand on wells which may enable ground water levels to be sustained. It also helps in the availability of potable water as rainwater is substantially free of salinity and other salts.

That's what our favourite online encyclopedia says about it.  Basically we are saving rainwater to run the toilets and the washing machine.

You need one big container, buried in a big hole, connected to the water supply and the drain pipes that pumps water when needed.   As the new house will be on a water meter, this will allow us to use water "off meter", this saves money and is ecologically sound.

This is what the gizmo looks like, and the hole that is sits in.

A couple more pics...